Surface Roughening and Composition Modulation of ZnSe-related II-VI epitaxial films

1996 ◽  
Vol 448 ◽  
Author(s):  
Shigetaka Tomiya ◽  
Hironori Tsukamoto ◽  
Satoshi Itoh ◽  
Kazushi Nakano ◽  
Etsuo Morita ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Surface Reconstruction ◽  
Epitaxial Films ◽  
Surface Roughening ◽  
Force Microscopy ◽  
Composition Modulation ◽  
Atomic Force ◽  
Transmission Electron ◽  
Rich Condition ◽  
Lattice Matched

AbstractWe have investigated ZnSSe and ZnMgSSe epitaxial layers lattice-matched to GaAs (001) substrates grown by molecular beam epitaxy using atomic force microscopy and transmission electron microscopy. Under II-rich conditions with c(2x2) surface reconstruction, surface morphology exhibited corrugation aligned in the [1ī0] direction and composition modulation was observed in the same [1ī0] direction. Under VI-rich condition with (2x1) surface reconstruction, the surface morphology becomes rounded grain-like and composition modulation was not observed. The formation of composition modulation is associated with the surface corrugated structures.

Anisotropic Behaviour of Surface Roughening in Lattice Mismatched Heteroepitaxial Thin Films

1996 ◽  
Vol 436 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
William D. Nix ◽  
Huajian Gao
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Lattice Mismatch ◽  
Surface Roughening ◽  
Silicon Substrates ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Annealing Experiments

AbstractHeteroepitaxial Si1-xGex. thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening can take place in the form of ridges which can be aligned along <100> or <110> directions, depending on the film thickness. In this paper, we investigate this anisotropic dependence of surface roughening and present an analysis of it. We have studied the surface roughening behaviour of 18% Ge and 22% Ge thin films subjected to controlled annealing experiments. Transmission electron microscopy and atomic force microscopy have been used to study the morphology and microstructure of the surface ridges and the dislocations that form during annealing.

scholarly journals Surface Morphology of MBE-grown GaN on GaAs(001) as Function of the N/Ga-ratio

1998 ◽  
Vol 3 ◽  
Author(s):  
O. Zsebök ◽  
J.V. Thordson ◽  
T.G. Andersson
Keyword(s):  
Surface Morphology ◽  
Surface Reconstruction ◽  
Defect Formation ◽  
Flux Ratio ◽  
Excitation Power ◽  
Rf Plasma ◽  
Molecular Beam Epitaxy Growth ◽  
Initial Growth ◽  
Force Microscopy ◽  
Atomic Force

Molecular beam epitaxy growth utilising an RF-plasma nitrogen source was used to study surface reconstruction and surface morphology of GaN on GaAs (001) at 580 °C. While both the nitrogen flow and plasma excitation power were constant, the grown layers were characterised as a function of Ga-flux. In the initial growth stage a (3×3) surface reconstruction was observed. This surface periodicity only lasted up to a maximum thickness of 2.5 ML, followed by a transition to the unreconstructed surface. Samples grown under N-rich, Ga-rich and stoichiometric conditions were characterised by high-resolution scanning electron microscopy and atomic force microscopy. We found that the smoothest surfaces were provided by the N/Ga-ratio giving the thickest layer at the (3×3)=>(1×1) transition. The defect formation at the GaN/GaAs interface also depended on the N/Ga-flux ratio.

Surface Morphology of SiGe Epitaxial Layers Grown on Uniquely Oriented Si Substrates

2000 ◽  
Vol 648 ◽  
Author(s):  
Morgan E. Ware ◽  
Robert J. Nemanich
Keyword(s):  
Surface Morphology ◽  
Lattice Mismatch ◽  
Morphological Structure ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Relationship Of

AbstractThe 4% lattice mismatch between Si and Ge creates strain in epitaxial layers of SiGe alloys on Si, and this strain can manifest itself in the morphological structure of the surface of the epitaxial layer. This study explores the relationship of the evolution of the surface morphology of SiGe layers grown on a range of Si surface orientations. We have grown thin, strained and thick, relaxed layers of Si0.7Ge0.3 by solid source molecular beam epitaxy on substrates with surface normals rotated from [001] towards [111] by angles of θ = (0, 2, 4, 10, 22) degrees. The surface morphology was investigated by atomic force microscopy, which showed considerable ordering of surface features on relaxed samples. These features evolve from hut-like structures at 0 degrees to large mesa-like structures separated by pits and crevices at 22 degrees. The organization of these features is also shown to vary with the substrate orientation. Each surface has characteristic directions along which features are aligned, and these directions vary continuously with the angle of rotation of the substrate. Transmission electron microscopy confirmed that misfit dislocations had formed along those same directions. The state of relaxation of each layer is quantified by Raman spectroscopy in order to make a direct correlation between residual strain and surface morphology.

Molecularly resolved observation of surface reconstruction of C60 epitaxial films by atomic force microscopy

1997 ◽  
Vol 385 (2-3) ◽  
pp. L945-L951 ◽  
Author(s):  
Y. Kim ◽  
L. Jiang ◽  
T. Iyoda ◽  
K. Hashimoto ◽  
A. Fujishima
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Reconstruction ◽  
Epitaxial Films ◽  
Force Microscopy ◽  
Atomic Force

Stress-driven surface evolution in heteroepitaxial thin films: Anisotropy of the two-dimensional roughening mode

1999 ◽  
Vol 14 (8) ◽  
pp. 3247-3256 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
William D. Nix ◽  
Huajian Gao
Keyword(s):  
Defect Formation ◽  
Ex Situ ◽  
Surface Roughening ◽  
Misfit Dislocations ◽  
Two Dimensional ◽  
Anisotropic Behavior ◽  
Surface Evolution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

We have analyzed the anisotropic behavior of surface roughening in Si1−xGex/Si(001) heterostructures by use of methods of elastic analysis of undulated surfaces and perturbation analysis on the basis of global energy variations associated with surface evolution. Both methods have shown that the two-dimensional stage of surface roughening preferentially takes place in the form of ridges aligned along the two orthogonal 〈100〉 type directions. This prediction has been confirmed by ex situ experimental observations of surface evolution by use of atomic force microscopy and transmission electron microscopy in both subcritically and supercritically thick Si1−xGex films grown on Si(001) substrates. Further experiments in supercritically thick films have revealed a remarkable interplay between defect formation and surface evolution: the formation of a network of 〈110〉?misfit dislocations in the latter stages alters the evolution process by rotating the ridge formations toward the 〈110〉 type directions.

Effect of ion fluence on the surface morphology of single crystal magnesium oxide implanted with xenon

1995 ◽  
Vol 10 (11) ◽  
pp. 2823-2828 ◽  
Author(s):  
Wenbiao Jiang ◽  
M. Grant Norton ◽  
David B. Poker
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Morphology ◽  
Single Crystal ◽  
Magnesium Oxide ◽  
Dislocation Loop ◽  
Spherical Indenter ◽  
Surface Roughening ◽  
Force Microscopy ◽  
Atomic Force ◽  
Oriented Single Crystal

The surface morphology (001)-oriented single-crystal magnesium oxide (MgO) implanted with xenon ions has been examined using atomic force microscopy. It was found that at the lowest fluence used in this study (1.0 × 1014/cm2), a slight roughening of the (001) surface occurred. The magnitude of this roughening remained fairly constant with increases in fluence in the range 1.0 × 1014/cm2 to 3.0 × 1016/cm2. Implantation at fluences of ≥ 1.0 × 1017/cm2 caused significant surface roughening with the concomitant formation of micron-sized blisters. The appearance of some of these blisters resembles the rosette pattern that is also observed when the cleaved surfaces of MgO crystals are etched following indentation using a spherical indenter. This observation suggests that these blisters are formed by the growth of xenon inclusions, during implantation, by a dislocation loop punching mechanism.

Correlation between Extended Defects and Surface Morphology in MBE Grown InAs/GaAs Heterostructures

1995 ◽  
Vol 399 ◽  
Author(s):  
M.R. Bruni ◽  
G. Padeletti ◽  
M.G. Simeone ◽  
L. Francesio ◽  
P. Franzosi ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Growth Temperature ◽  
Crystal Defects ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTInAs single layers were grown by Molecular Beam Epitaxy on nominally (001) oriented GaAs substrates at growth temperatures ranging from 350 °C to 500 °C and thicknesses between 1 nm and 6 μm. A systematic study of the influence of growth temperature and thickness on crystal defects and surface morphology is discussed by comparing High Resolution X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy investigations.Surface hexagonal shaped holes were observed to develop at the lowest temperatures starting from an heterolayer thickness of 50 nm. Both misfit and threading dislocations were revealed; moreover the correlation between hexagonal shaped surface holes and mixed dislocations, with the component of the Burgers vector (b) along the growth axis larger than the minimum interatomic distance, is discussed. The holes increase in size and decrease in density by increasing the layer thickness. An almost complete surface planarization is observed at a thickness of 6 μm by increasing the growth temperature up to 500 °C.

Epitaxial Growth and Characterization of Lattice-Matched MgO/Cr0.7Mo0.3/MgO(001) Layered Structures

1994 ◽  
Vol 357 ◽  
Author(s):  
S.A. Chambers ◽  
Y. Liang ◽  
Y. Gao
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Structural Coherence ◽  
Crystallographic Order ◽  
Lattice Matched

AbstractWe have grown by molecular beam epitaxy (MBE) structurally coherent layers of MgO and a random bcc alloy of 70% Cr and 30% Mo to which MgO is lattice matched. Specimens werecharacterized by means of reflection high-energy electron diffraction (RHEED), x-ray photoelectron spectroscopy and diffraction (XPS/XPD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). These systems exhibit excellent long- and shortrange crystallographic order, as well as nearly perfect structural coherence across the interface.

AFM observations of the surface morphology of metallic glasses Fe78B13Si9 in the early stage of crystallization

1992 ◽  
Vol 7 (8) ◽  
pp. 2126-2130 ◽  
Author(s):  
Yoshihisa Watanabe ◽  
Yoshikazu Nakamura
Keyword(s):  
Surface Morphology ◽  
Metallic Glasses ◽  
Crystallization Process ◽  
Early Stage ◽  
Spatial Density ◽  
Exoelectron Emission ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Surface Image

The change in the surface morphology of metallic glasses Fe78B13Si9 during the early stage of the crystallization process has been studied mainly by atomic force microscopy (AFM). Specimens of 50-μm thickness have been heated up to 323 K, 373 K, 423 K, and 523 K with a heating rate of 30 K/min in vacuum, and then the surface morphology of each specimen has been observed by AFM in air. In the surface image of the specimen heated to 323 K, many holes are observed and inside the holes single or plural protrusions can be observed. Clusters composed of aggregated protrusions are also found like islands in the amorphous sea. The specimen heated to 323 K has also been observed by a high-resolution transmission electron microscope and crystalline structures among the amorphous matrix have been detected. From the selected area diffraction study, the crystalline structure is found to be α–Fe crystallites. In contrast, in the AFM image of the surface of the specimen heated to 423 K, no holes are seen and many protrusions are found to extend above the surface and form several parallel lines. The spatial density of protrusions above the surface becomes much higher in the specimen heated to 523 K. We propose that this change in the surface morphology during heat treatments indicates the process of nucleation and growth of α–Fe crystallites in the surface of metallic glasses. It is also found that the stage of many protrusions extending above the surface corresponds with the beginning of exoelectron emission from the surface. This result suggests that exoelectron emission and surface crystallization connect with each other.

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